An operating system is a collection of software that manages device hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a device. The system software manages and integrates a computer's capabilities. The system software includes the operating system, utility software, device drivers, and other software tools. Application software can be considered to be all the computer software that causes a computer to perform useful tasks in response to user requests. A specific instance of application software is called a software application, application program, application or app, which are used interchangeably below. Application programs usually require an operating system to function.
As more and more services are becoming available for small or mobile devices, the number of applications running in a single device has increased significantly. Usually, a mobile device is used mostly for certain specific applications, while being equipped with general purpose computing capabilities. For example, it is common to find a mobile phone that also runs a browser application, a gaming application, and a media player application, etc. On the other hand, a mobile video player device may run a gaming application and/or an email application in addition to a video application. Multiple applications or processes in the same device compete with each other by sharing the same memory resources and computation resources embedded inside the device. The operating system performs resource/memory management to deal with resource contention in concurrent computing. Examples of resource/memory management techniques are described in U.S. Pat. No. 7,827,358, and U.S. publication numbers 2012/0179882 and 2013/0332936, all of which are incorporated herein by reference.
Usually there are several application programs running in the background of a device to perform various functions such as VoIP (Voice over Internet Protocol), maps, music, notifications, etc. Application programs that consume CPU or other resources of the device while running in the background can drain a significant amount of battery without the user's knowledge and/or can also affect the performance of an application running in the foreground such that the foreground application appears to the user to run slower or significantly slower as a result of background applications that consume significant CPU (or other) resources. When that happens, users experience decreased performance and/or decreased battery life with no tangible benefits.